Preparation and characteristics of a wheat embryo cell-free extract active in the synthesis of high molecular weight viral polypeptides.

Abstract Wheat embryo extracts are commonly used in cell-free protein synthesis studies. Soluble inhibitor(s) that diminish aminoacylation of tRNA exist in such extracts. These inhibitors can be effectively removed by prolonged dialysis, provided that proper salt conditions are maintained to ensure stability of the extract. The system, when only partially depleted of inhibitors, does not effectively support translation of certain classes of messengers, i.e., brome mosaic virus RNA 1 and RNA 2. All four proteins expected as the products of translation of BMV RNA, including peptides of molecular weight approaching 120,000, are formed in the fully active system. At limiting concentrations of template, the fully activated system incorporates the following amounts of [ 14 C]leucine per microgram of template: Qβ RNA, 4.5 pmol; reovirus mRNA, 200 pmol, tobacco mosaic virus RNA, 227 pmol, and brome mosaic virus, up to 350 pmol.